1. Field of the Invention
The present invention relates to cores embedded in a crawler body and also to the structure of a rubber crawler using the cores therein.
2. Description of the Prior Art
Many types of cores 10 for a rubber crawler have so far been proposed; however, they have a pair of protrusions 101 facing with each other and which are provided near the center of a core body 100 as shown in FIG. 17. A rubber crawler 20 using such cores 10 is used as shown in FIGS. 18 and 19. More specifically, an endless rubber crawler body 21 has lugs 22 provided on the outer surface thereof and also holes 23 provided in the crawler body 21 along the center line thereof to be equally spaced apart from each other. Sprocket teeth are engaged in the holes 23. Such cores 10 are embedded in the crawler body 21 between the respective two adjacent engagement holes 23. The rubber crawler 20 is held between a drive tumbler 30 and a take-up tumbler 40, and sprocket teeth 31 of the drive tumbler 30 are engaged in the holes 23. And lower rollers 50 roll on the inner surface of the rubber crawler 20.
Such rubber crawler 20 has been used lately in civil engineering and construction vehicles. Consequently, the crawlers have become larger than those used in conventional vehicles. Also as the weight of the civil engineering and construction vehicles increased, the crawlers became extremely wide. Therefore, the rubber crawlers were required bearing a very high load. For coping with the increased size of such vehicles, the length and strength of the cores embedded in the crawler should be increased correspondingly. To solve these problems, it has been proposed to increase the thickness of the core, or to embed two cores in the direction of the width of the crawler, and various other solutions have been proposed heretofore.
The conventional solution to cope with the larger size of the vehicles by increasing the core thickness results in the increase in thickness of the crawler itself, which unavoidably leads to the increase in manufacturing costs of the rubber crawler. Also this solution is disadvantageous in that the increased flexural rigidity of the crawler caused a loss of rotation resistance. Further, the solution by using two cores embedded in the direction of the crawler width results in no problem due to the increased flexural rigidity; however, bending of the crawler at the center thereof causes various drawbacks.